MAGNAMOSIS IV: magnetic compression anastomosis for minimally invasive colorectal surgery

BACKGROUND AND STUDY AIMS

MAGNAMOSIS forms a compression anastomosis using self-assembling magnetic rings that can be delivered via flexible endoscopy. The system has proven to be effective in full-thickness porcine small-bowel anastomoses. The aim of this study was to show the feasibility of the MAGNAMOSIS system in hybrid endoscopic colorectal surgery and to compare magnetic and conventional stapled anastomoses.

METHODS

A total of 16 swine weighing 35 - 50 kg were used following animal ethical committee approval. The first animal was an acute model to establish the feasibility of the procedure. The subsequent 15 animals were survival models, 10 of which underwent side-to-side anastomoses (SSA) and 5 of which underwent end-to-side (ESA) procedures. Time to patency, surveillance endoscopy, burst pressure, compression force, and histology were assessed. Histology was compared with conventional stapled anastomoses. Magnetic compression forces were measured in various anastomosis configurations.

RESULTS

Colorectal anastomoses were performed in all cases using a hybrid NOTES technique. The mean operating time was 71 minutes. Mean time to completion of the anastomosis was similar between the SSA and ESA groups. Burst pressure at 10 days was greater than 95 mmHg in both groups. One complication occurred in the ESA group. Compression force among various configurations of the magnetic rings was significantly different (P < 0.05). Inflammation and fibrosis were similar between magnetic SSA and conventional stapled anastomoses.

CONCLUSION

MAGNAMOSIS was feasible in performing a hybrid NOTES colorectal anastomosis. It has the advantage over circular staplers of precise endoscopic delivery throughout the entire colon. SSA was reliable and effective. A minimum initial compression force of 4 N appears to be required for reliable magnetic anastomoses.

Alterations in maternal-fetal cellular trafficking after fetal surgery

BACKGROUND/PURPOSE

Bidirectional trafficking of cells between the mother and the fetus is routine in pregnancy and a component of maternal-fetal tolerance. Changes in fetal-to-maternal cellular trafficking have been reported in prenatal complications, but maternal-to-fetal trafficking has never been studied in the context of fetal intervention. We hypothesized that patients undergoing open fetal surgery would have altered maternal-fetal cellular trafficking.

METHODS

Cellular trafficking was analyzed in patients with myelomeningocele (MMC) who underwent open fetal surgical repair (n = 5), patients with MMC who had routine postnatal repair (n = 6), and healthy control healthy patients (n = 9). As an additional control for the fetal operation, trafficking was also analyzed in patients who were delivered by an ex utero intrapartum treatment procedure (n = 6). Microchimerism in maternal and cord blood was determined using quantitative real-time polymerase chain reaction for nonshared alleles.

RESULTS

Maternal-to-fetal trafficking was significantly increased in patients who underwent open fetal surgery for MMC compared with healthy controls, patients who underwent postnatal MMC repair, and patients who underwent ex utero intrapartum treatment. There were no differences in fetal-to-maternal cell trafficking among groups.

CONCLUSION

Patients undergoing open fetal surgery for MMC have elevated levels of maternal microchimerism. These results suggest altered trafficking and/or increased proliferation of maternal cells in fetal blood and may have important implications for preterm labor.

Magnamosis III: delivery of a magnetic compression anastomosis device using minimally invasive endoscopic techniques

PURPOSE

Magnamosis creates a secure sutureless anastomosis through magnetic compression. In this study, we further develop and test delivery devices capable of creating a secure duodeno-colonic anastomosis using available minimally invasive endoscopic techniques.

METHODS

Eight pigs underwent general anesthesia. Colonoscopy was used to deliver 1 magnetic ring to the hepatic flexure. Simultaneously, upper endoscopy delivered the other magnetic ring into the duodenum using a variety of techniques. The 2 magnetic rings were brought into magnetic proximity under laparoscopic guidance. The pigs were recovered and examined daily followed by sacrificing at 1, 2, 4, and 6 weeks.

RESULTS

The device designed to deliver and release each magnetic ring evolved from using a guide wire and balloon devices to redesigning the magnetic ring casing with a groove to accommodate an endoscopic snare. Laparoscopic visualization assured safe magnet mating of intestinal segments. The duodeno-colonic anastomoses created with the snare yielded widely patent anastomoses. In vitro testing revealed excellent burst pressure. Histology revealed complete healing as early as 1 week.

CONCLUSION

We redesigned the magnamosis device to facilitate delivery by endoscopic techniques. The snare technique allows endoscopic positioning and controlled release of the magnetic rings for a secure side-to-side duodeno-colonic anastomosis.

Magnetic mini-mover procedure for pectus excavatum III: safety and efficacy in a Food and Drug Administration-sponsored clinical trial

PURPOSE

The magnetic mini-mover procedure (3MP) uses magnetic force to gradually remodel pectus excavatum deformity. A magnet is implanted on the sternum and coupled with an external magnetic brace. Under Investigational Device Exemption and Institutional Review Board approval, we performed a pilot study of safety, probable efficacy, and cost-effectiveness of this new treatment of an orphan disease using an implantable pediatric device.

METHODS

Ten otherwise healthy patients, ages 8 to 14 years, with severe pectus excavatum (pectus severity index [PSI] > 3.5) underwent 3MP treatment (mean, 18.8 ± 2.5 months). Safety was assessed by postimplant and postexplant electrocardiograms and monthly chest x-rays. Efficacy was assessed by change in pectus severity index as measured using pretreatment and posttreatment computed tomographic scan. Cost of 3MP was compared with that of standard procedures.

RESULTS

The 3MP device had no detectable ill effect. Device weld failure or malpositioning required revision in 5 patients. Average wear time was 16 h/d. Pectus severity index improved in patients in the early or mid puberty but not in patients with noncompliant chest walls. Average cost for 3MP was $46,859, compared with $81,206 and $81,022 for Nuss and Ravitch, respectively.

CONCLUSION

The 3MP is a safe, cost-effective, outpatient alternative treatment for pectus excavatum that achieves good results for patients in early and midpuberty stages.

Guide wire assisted catheterization and colored dye injection for vascular mapping of monochorionic twin placentas

Monochorionic (MC) twin pregnancies are associated with significantly higher morbidity and mortality rates than dichorionic twins. Approximately 50% of MC twin pregnancies develop complications arising from the shared placenta and associated vascular connections. Severe twin-to-twin syndrome (TTTS) is reported to account for approximately 20% of these complications. Inter-twin vascular connections occur in almost all MC placentas and are related to the prognosis and outcome of these high-risk twin pregnancies. The number, size and type of connections have been implicated in the development of TTTS and other MC twin conditions. Three types of inter-twin vascular connections occur: 1) artery to vein connections (AVs) in which a branch artery carrying deoxygenated blood from one twin courses along the fetal surface of the placenta and dives into a placental cotyledon. Blood flows via a deep intraparenchymal capillary network into a draining vein that emerges at the fetal surface of the placenta and brings oxygenated blood toward the other twin. There is unidirectional flow from the twin supplying the afferent artery toward the twin receiving the efferent vein; 2) artery to artery connections (AAs) in which a branch artery from each twin meets directly on the superficial placental surface resulting in a vessel with pulsatile bidirectional flow, and 3) vein to vein connections (VVs) in which a branch vein from each twin meets directly on the superficial placental surface allowing low pressure bidirectional flow. In utero obstetric sonography with targeted Doppler interrogation has been used to identify the presence of AV and AA connections. Prenatally detected AAs that have been confirmed by postnatal placental injection studies have been shown to be associated with an improved prognosis for both twins. Furthermore, fetoscopic laser ablation of inter-twin vascular connections on the fetal surface of the shared placenta is now the preferred treatment for early, severe TTTS. Postnatal placental injection studies provide a valuable method to confirm the accuracy of prenatal Doppler ultrasound findings and the efficacy of fetal laser therapy. Using colored dyes separately hand-injected into the arterial and venous circulations of each twin, the technique highlights and delineates AVs, AAs, and VVs. This definitive demonstration of MC placental vascular anatomy may then be correlated with Doppler ultrasound findings and neonatal outcome to enhance our understanding of the pathophysiology of MC twinning and its sequelae. Here we demonstrate our placental injection technique.

Totally Endoscopic Magnetic Enteral Bypass by External Guided Rendez-Vous Technique

Objective. This study aimed to assess the feasibility of a totally endoscopic enteral bypass using a self-orienting, dual ring, magnetic anastomosis system (MAGNAMOSIS) guided by a magnetic tracking system (3D METRIS). Materials and methods. In an anesthetized pig, 2 endoscopes were advanced, one each into the stomach and the colon. Both endoscopes were equipped with a MAGNAMOSIS ring secured with an endoscopic snare and a 3D METRIS within one working channel. The whole procedure was followed laparoscopically. The tracking system guided tips of endoscopes to a “rendez-vous” location between the colon and stomach. Results. MAGNAMOSIS magnets automatically joined in the correct configuration when guided to within 2 cm of each other. At necropsy, magnetic rings were secure without entrapment of excess bowel or mesentery. Conclusion. An endoscopic enteral bypass with magnetic anastomosis and magnetic tracking device was feasible. More accurate tracking and advanced techniques could enable endoscopic bypasses at multiple sites in the gastrointestinal tract.

NF-kappaB activation precedes increases in mRNA encoding neurokinin-1 receptor, proinflammatory cytokines, and adhesion molecules in dextran sulfate sodium-induced colitis in rats

Nuclear factor kappa B (NF-kappa B) plays a key role in initiating inflammation associated with colitis. A systematic study was conducted in the rat DSS colitis model to determine the temporal relationship between NF-kappa B activation and expression of substance P (SP), neurokinin-1 receptor (NK-1R), proinflammatory cytokines, and adhesion molecules. Rats were given 5% DSS in their water and sacrificed daily for 6 days. Colon tissue was collected for assessment of histological changes, NF-kappa B activation, myeloperoxidase (MPO) activity, and expression of NK-1R, SP, TNFalpha, IL-1beta, VCAM-1, ICAM-1, E-selectin, CINC-1, MIP-1alpha, and iNOS. NF-kappa B activation increased, biphasically, on Day 1 and again on Days 4-6. The mRNA levels for ICAM-1, CINC-1, IL-1beta, TNFalpha, VCAM-1, and NK-1R rose significantly (P < 0.05) by 2-4 days. Increased iNOS mRNA levels, MPO activity, and mucosal damage occurred on Day 6. These data demonstrate that NF-kappa B activation substantially precedes the onset of physical disease signs and active inflammation.

Photopolymers in orthopedics: characterization of novel crosslinked polyanhydrides

Novel, high modulus, degradable polymers were prepared from methacrylated anhydride monomers of tricarballylic acid (MTCA) and pyromellitylimidoalanine (MPMA-ala). Kinetic studies indicate that the time scale of photopolymerization of MTCA (< 30 s) is suitable for in vivo applications. Additionally, the tensile modulus of copolymers of these novel monomers with methacrylic anhydride (MA) ranged from 0.8 to 2.1 GPa, which lies between the modulus of trabecular and cortical bone. Degradation studies indicate that the copolymers of MTCA and MPMA-ala with MA are initially surface degrading, which is important to maintaining polymer strength through the degradation process. Monomers such as these that can be rapidly polymerized using ultraviolet or blue light into high modulus degradable materials have great potential in orthopedics.